1. Field of the Invention
The present invention relates to a controlling device for a substrate processing apparatus that performs a specified process on a substrate, to a control method, and to a storage medium that stores a control program. More particularly, the present invention relates to an optimal adjustment of a feed forward control of the same substrate processing apparatus.
2. Description of the Related Art
When a desired process is performed in succession on a plurality of substrates, a reaction product that is generated during the process gradually adheres to an interior wall of a substrate processing apparatus, thereby gradually changing the atmosphere inside the substrate processing apparatus. A feed forward control and a feedback control have been proposed for some time in order to perform the substrate processing with constantly good precision while adapting to the changing atmosphere (for example, refer to Japanese Patent Application Publication No. JP-A-2004-207703.)
In the feedback control, for example, in a case where an etching process is performed on the substrate, the state of the substrate surface is measured by a measuring instrument before and after the etching process. The measurements of the state of the substrate surface before and after processing are used to determine the extent to which the actual amount of material removed from the substrate deviates from a target value. Based on the amount of the deviation, a feedback value, such as the etching amount per unit time, for example, is computed, and the computed feedback value is used in an updating of the target value. In this manner, the target value is constantly optimized so that it reflects the current changes in the atmosphere inside the substrate processing apparatus.
In the feed forward control, the most recent target value determined by the feedback control is defined as a control value, and the specified processing of the substrate is performed based on the control value. For example, in a case where the target value is the etching amount per unit time, even if the atmosphere in the substrate processing apparatus gradually changes, the substrate is processed well according to the etching amount per unit time, which is varied according to the changes in the atmosphere inside the substrate processing apparatus.